## Precalculus (6th Edition) Blitzer

The theoretical probability of event $E,\ \text{}\ \text{denoted}\ \text{by}$ $P\left( E \right)$, is the $\text{number}\ \text{of}\ \text{outcomes}\ \text{in}\ \text{event}\ E$ divided by the total number of possible outcomes.
We know that if an event $E$ has $n\left( E \right)$ equally likely outcomes and its sample space $S$ has $n\left( S \right)$ equally likely outcomes, theoretical probability of event $E$ is denoted by $P\left( E \right)$ as given below; $P\left( E \right)=\frac{\text{number}\ \text{of}\ \text{outcomes}\,\text{in}\ \text{event}\,E}{\text{number}\ \text{of}\text{outcomes}\ \text{in}\ \text{sample}\ \text{space}\ S}$